1. Field of the Invention
The present invention relates to a teeth-bleaching set and the method for using such a teeth-bleaching set in removing (bleaching), by employing photocatalytic and hydrogen peroxide reactions, coloration and discoloration of teeth resulting from the deposition of pigments on the teeth.
2. Description of Conventional Art
Generally, whiteness of teeth is an important cosmetic element desired especially by young women and cases of seeking treatments for having whiter teeth increase. A method commonly in use is to use hydrogen peroxide solution.
In other words, in a common teeth-bleaching method, hydrogen peroxide with light or heat is utilized. In this method, a piece of gauze impregnated with hydrogen peroxide solution is placed on the labial surface of the teeth, and is irradiated, from side to side, with a lamp for about 30 minutes. This requires that the lamp used must be kept as close to the teeth as possible, and the hydrogen peroxide solution must be replenished approximately every five minutes to keep the gauze moist.
There is also a method, in which the irradiation of light from a lamp is replaced by applying a high frequency current for one (1) second with a high frequency electric cautery knife equipped with a spoon-shaped tip, then pausing for eight (8) seconds, and repeating this process for 6˜8 times. In yet another method, in place of a piece of gauze impregnated with hydrogen peroxide solution, a solution (paste) made by mixing a thickener with hydrogen peroxide solution is used as an agent, and is applied directly to the teeth surface.
Besides the above, there are numerous bleaching agents and methods that have been proposed in using combinations of hydrogen peroxide solution, a variety of instruments, and other agents. Among them are: a bleaching method in which a mixture of hydrochloric acid, hydrogen peroxide solution, and diethylether is used as a bleaching agent; a method in which a paste made from kneading together sodium perborate powder and 30% by weight of hydrogen peroxide solution is used as a bleaching agent; a bleaching agent in which a mixture of hydrogen peroxide solution with orthophosphoric acid is used and a bleaching method with using it, as seen in Japanese Patent Laid-Open JP-A-08143436; a bleaching agent made by a mixture of anhydrous silicic acid with hydrogen peroxide solution and a method of bleaching a vital teeth by application of said bleaching agent, as seen in Japanese Patent Laid-Open JP-A-05320033; and dental bleaching compositions made from a dental bleaching agent (such as urea hydrogen peroxide, hydrogen carbamide peroxide and carbamide peroxide.) and a matrix material (such as carboxymethylene.), and their respective application methods, as seen in Japanese Patent Laid-Open JP-A-08113520, etc. But these conventional methods that employ hydrogen peroxide have a common shortcoming in that they require a lengthy bleaching time. Also, there is a bleaching method practiced in the United States in which urea peroxide of about 10% by weight concentration is used instead of hydrogen peroxide, but due to lengthy time required as in the use of hydrogen peroxide, the results are not satisfactory.
Instead of using hydrogen peroxide solution in bleaching as mentioned above, a dental bleaching method by using a titanium dioxide powder having photocatalytic activities and hydrogen peroxide in low concentration has been proposed, as seen in Japanese Patent Laid-Open JP-A-11092351. However, the conventional bleaching agent employing the titanium dioxide has a poor bleaching efficiency and, in order to meet the satisfactory whitening demanded by patients, a lengthy bleaching time is also needed.